The model BPS TE-TE spherical cavity ionization chambers have been constructed in Institute of Biophysics, Academia Sinica. The basic performences of the chambers have been measured. The results of measurement of the saturation characteristics show that the relation between Q,s,/Q,v, and V,-2, is linear in ,60,Co photon field and between I,s,/I,v, and V,-1, is linear in D+T neutron photon mixed field. The correlation coefficients is extremely close to l. The saturation correction factors were obtained.,The wall thickness correction factors for determination of free-in-air are (0.60 ±0.88) ×10,-2,mm,-1, and (0.49±0.35) ×10,-2,mm,-1, for 15 MeV neutrons and ,60,Co photons respectively. The relative change of the response with angle of irradiation is not larger than 0.5 per cent when incident degrees of the radiation is in the range of 0~120° for the ,60,Co gamma rays but is about one per cent for the 15 MeV neutrons. The influences of stem scatter and radiation sensitivity of stem were studied in photon and neutron fields for irradiation free-in-air. The ratios of readings with TE gas and air were measured for TE-gas and calculated with the ratios of CH,4, CO,2, N,2, given by Williams. The values measured and calculated are coincident. The effect of TE gas flow rate on the readings of the chamber was observed.